Pursuant § 1 EIRAG, EU based non-Austrian lawyers can directly, i.e. without appointing a local representative in Austria, reply to office actions of the Austrian Patent Office. The only prerequisite is a registration of the foreign lawyer by the Austrian bar association, which, however, does not even incur any official fees.
The possibilities for EU based lawyers to act directly before the trademark offices of foreign countries are manifold. Although the formal requirements differ from country to country, at least for German lawyers it is often, like in Austria, not very difficult to meet these requirements.